specifying webdata imagetypes

I want to filter the imagetype that the webdata component fetches. The options are:

itALL, itJPG, itGIF and itPNG  . I want to allow only jpg and gifs to be gathered, how can I specify these parameters instead of itALL? This way I can filter out what is shown.
Allowing for bmp's and other formats would be a great addition also.
Unfortunately the png option is redundant as the webimage component doesn't allow it.
thanks
 
 

I guess I can't have jpg's and gifs as a choice of two imagetypes then?

Can this be added in an update please?